Signaling system



C. S. DEMAREST SIGNALING SYSTEM June 20, 1933.

Filed Oct. 1, 1932 4 Sheets-Sheet 1 INVENTOR C. @flenwuaest ATTORNEY June 20, 1933. c. s. DEMAREST 1,914,407

S IGNALING SYSTEM Filed Oct. 1, 1932 4 Sheets-Sheet 2 INVENTOR C. qiflemwxas ATTORNEY June 20, 1933. c, s, DEMAREST SIGNALING SYSTEM 4 Sheets-Sheet 3 Filed Oct. 1, 1932 INVENTOR 5. lifienmices ATTORRfEY June 20, 1933. Q 5 DEMAREST 1,914,407

SIGNALING SYSTEM Filed Oct. 1, 1952 4 Sheets-Sheet 4 INVENTOR C Sfienmres BY ATTORNEY Patented June 20, 1933 UNITED STATES CHARLES S. DEMAREST, OF RIDGEWOOD,

NEW JERSEY, ASSIGNOR TO AMERICAN SIGNALING SYSTEM:

Application filed October 1, 1932.

This invention relates to signaling systems and more particularly to visual signaling systems such as picture transmission or television systems.

In visual signaling systems the three dimensions of length, breadth and light intensity are required to be converted into two dimensions, current strength and time in order to be transmitted over a line circuit. This conversion is accomplished by scanning. The process of scanning consists of effectively dividing the picture into a large number of elements arranged in two dimensional rows or strips which are exposed consecutively to the light sensitive transmitting device, thus sending a series of signals of varying current intensity over the line circuit. At the receiving station these signals are rearranged in rows or strips by the receiving apparatus operating in synchronism with the transmitting apparatus, thus regaining the three dimensions of the original picture.

The scanning devices used at both transmitting and receiving stations for television have usually employed mechanical means such as large, spirally-perforated discs through which the various elements of the picture are illuminated or viewed. A high degree of synchronism is required with such devices in order to avoid distortion or displacement of the image. For slower picture transmission or telephotography, other devices may be used such as a light-sensitive transmitting device, synchronously rotating films and light values operated by the received currents.

In the arrangements disclosed in this invention the mechanical devices heretofore used are replaced by gas-filled tubes to provide for closer synchronism, more rapid scanning, and the elimination of moving parts in the system. Other objects and features of the invention will appear more fully from the detailed description thereof hereinafter given.

The invention may be more fully understood from the following description together with the accompanying drawings in the Figures 1, 2, 3 and 4 of which the inven tion is illustrated. Figs. 1 and 2 are circuit Serial No. 635,834.

diagrams showing respectively transmitting and receiving arrangements of the invention suitable for television or picture transmission systems. Figs. 8 and at are transmitting and receiving arrangements for scanning large areas in telephoto or television systems. Similar reference characters have been used to denote like parts in all of the figures.

As the various transmission paths shown in F l are closed consecutively through tubes ,8 S the condition of switches T T T and the values of resistances R R R will determine the intensity of the signaling current transmitted over the line circuits. At the receiving station, as shown in Fig. 2, the varying currents are distributed to the signaling devices, such as glow lamps G G TN, in the proper time relation and produce the degree of illumination determined by the value of resistances at the transmitting station. VJhere variations in illumination are not required, these resistances may be of the same value or omitted.

The arrangements of the invention, as illustrated, might be used for a variety of purposes requiring instantaneous remote control of visual signals, such as bulletin boards, or advertising signs, each light element of which corresponds to one of the lamps G G etc. By the proper operation of keys T T T to form letters, numbers, etc, such signals might be displayed and changed at will. Some uses of such remote control are for dial call announcing systems, advertising sign displays, brokers bulletin boards, display boards on signal towers for the crews of moving trains, etc. The principles of this invention may also be applied to non-visual signaling systems. It is particularly adapted to use with printing telegraph systems, as will be explained more fully hereinafter.

By the combination of groups of such tube arrangements, each group for one section of the picture, large areas may be covered. Also by employing different frequencies for synchronizing and signaling in the two directions, simultaneous transmission and reception may be obtained.

Fig. 1 shows the arrangement of the transmitting station. Filters F and F are provided to separate the synchronizing and signaling frequencies. An interrupte synchronizing signal is transmitted to the input circuits of tubes S S S and simultaneously through filter F and over line L to the corresponding units such as tubes S S at the receiving station. As these tubes are successively operated and quenched, thus closing and opening transmission paths, 1, 2 N, the output of oscillator O is transmitted over the line L in varying intensity, amplified by the commonamplifier A at the receiving station and distributed to the proper transmission paths and glow tubes. The keys and resistances .at the transmitting station may be replaced by photoelectric cells or other devices whose resistance varies with the intensity of light falling upon them, thus controlling the output of oscillator O.

The detailed operation of the system is as follows: When key 6 is closed energy from source 7 is transmitted through interrupter 5 and key 6, transformer 8 and over leads 9 to the input rectifier circuits of all the tubes S S S At the same time this frequency is transmitted through filter F to the line L and thus to the receiving station where a corresponding filter F and transformer 8 are provided. The signals are thenapplied to the input rectifier circuits of receiving tubes S S S operating these in synchronism with those at the transmitting station.

At the transmitting station tubes'S and all succeeding tubes are provided with two input rectifier circuits in series which are so arranged that each of these tubes requires energy to be supplied from thaprecedmg auxiliary tubes Sn, S12, etc, in addition to the synchronizing voltage from source 7, in order to be operated. Tube S however, is operated at the first spurt of synchronizing voltage transmitted from source 7 by inter rupter 5. The alternating current voltage is transmitted over leads 9, through transformer 10, rectified by rectifier 11 and causes condenser 13 to be charged through resistance 12. The voltage across condenser 13 is opposite in polarity to that of battery l-it and causes the grid potential to become more pos1- tive until the voltage is reached at which ionization occurs in tube 8,, establishing an are between anode and cathode and closing the plate circuit of oscillator 0 through key T resistance R condensers C and tuned circuit L C The value of resistance R will determine the output of oscillator O which is transmitted through filter F and over line L during the time that tube S is operated. When the arc is established in tube S the circuit through transformers 15 and 16 and condensers 17 is also closed and attenuating current voltage from source 18 is then transmitted to the grid-cathode circuit of tube S causing it to ionize and close the circuit through transformers 19 and 20 and condenser 22. Voltage from source 21 is then applied through these transformers to the rectifier circuit comprising rectifier .43, resistance 24, condenser 25, and resistances 2G and 27, charging condenser 25and causing current to flow through resistances 26 and The voltage drop across resistance 27 is opposed to the voltage of battery 28 and when the resultant anode potential is sulficiently reduced the arc in the tube S is quenched,

2 opening the plate circuit of oscillator O and cutting off the current transmitted over line L. The values of resistances 24, 26 and 27 and condenser 25 are so chosen that tube S is quenched before the next spurt of synchronizing current is received from source 7. Energy from source 21 is also transmitted to the rectifier circuit associated with tube S consisting of rectifier 29, resistance 30, condenser 31, and resistances 32 and 33. A voltage drop is produced across resistance 33 in the same manner as described above for resistance The voltage drop across resistance 32; is controlled, however, to be not suflicient in itself to cause ionization of S \Vhen the second spurt of synchronizing voltage is impressed on the input rectifier circuit of tube S the voltage produced across condenser 37 by rectifier 35 supplies the additional voltage necessary to operate tube S which closes the plate circuit of oscillator 0 through key T resistance R condensers C and .tuned circuit L0,. The output of oscillator 0 then depends on the value of resistance R The operation of tube S causes the operation of tube S in a manner similar tofthat described above for tubes S and S and tube S is quenched in like manner before the next spurt of synchronizing voltage. The closing of the succeeding paths occurs similarly, each path being closed only at the application of successive spurts of synchronizing voltage, and being opened by the action of the preceding auxiliary tube before the next tube operates. Since the auxiliary tubes S S etc., remain operated, tubes S S etc., are prevented from operatin more than once in a cycle of operations. hen tube S is operated, voltage is applied from source 38 through transformers 39 and 40 to the rectifier circuits associated with the anode circuits of all the auxiliary tubes S S etc. These are then quenched simultaneously in a manner similarto that described above for tube S Voltage from source 38 is also applied to the rectifier associated. with the anode circuit of tube S itself, which is quenched after all the auxiliary tubes but before the next spurt of synchronizing voltage. Tube S is now ready'to be operated by the next spurt and the cycle will be repeated as transmitting 7 passes telephoto or television use.

- the transmitting station rupter described above, successive tubes operating on successive spurts.

At the receiving station the synchronizing' signals are transmitted through filter F and transformer 8 and are applied to the input rectifier circuits of tubes S S causing these tubes to operate in synchronisin with the corresponding tubes at the station. As the successive transmission paths are closed, the varying signals of frequency transmitted through filters F and F from oscillator O are amplified by the common amplifier A. whose output through transformers l1 into transmission paths including signal devices G G G such as lamps or glow tubes, which are then operated with intensities depending on the values of the corresponding resistances R R R at the transmitting station. v

In Figs. 3 and 4c, with Fig. 4: placed to the right of Fig. 3, are shown arrangements of the invention for scanning large areas as in p In the arrange- 3 auxiliary distributors D D D are provided each one scanning individual areas, such as U U U covering the total area desired to be scanned. Each of the auxiliary distributors, such as D would comprise a combination of gasiilled tubes A A similar .in arrangement respectively to the set of gas-filled tubes shown in Fig. S S Instead of the tubes in auxiliary distributor D being adapted to close circuits through the switches T T etc, these tubes would each close circuits for photoelectric cells or light responsive devices. For example, the tubes of D would close circuits for the photoelectric cells, such as 60, 61, etc., of individual area U The tubes of distributor D would close circuits through the light responsive devices of area U At there would be provided arrangements identical with those of Fig. 1 except that the operation of tube S would extend the operating circuit of the oscillator O to the distributor D The oscillator circuit would then be completed by the operation of the tubes, such as A etc., through the various light responsive devices. Depending upon the operation of these light responsive the strength of the curment. of Fig.

devices rent transmitted out over the line "from oscillator 0 would be varied. The tubes, A A A of the distributor D would operate through one complete cycle under control bi current from source 72 and inter- 71. After the completion oi: the cycle of operations of D the area U will have been scanned. lhe tube S will be adjusted to their release and S will operate. This will connect the oscillator O to the distributor D which will be similar to D and the area U will be scanned. This process will 1 and desi nated S continue until all-of the individual areas have been scanned. ()bviously to eliect the various light responsive devices in the various areas the image of the whole area may be focused or reflected on these cells.

At the receiving end of the system as shown in Fig. 4 there would be provided arrangements such as those shown in Fig. 2. For example, there would be provided a filter F transmitting current from the distant oscillator O to the common amplifier A. The output circuit of the amplifier would be extended through a series of tubes such as S S operated in synchronism with. the tubes S S in Fig. 3 by the synchronizing current transmitted through iilters F from source 7 and interrupter 5 of Fig. 3. The cathode-anode circuit of each of the tubes S S would be extended or completed through the tubes of the distributors D D respectively. Each of these dis- JlltOlS would comprise a set of tubes corresponding in action to the tubes of the corresponding distributors D D of Fig. 3. For example, tubes A A of distributor D would correspond to tubes A A of distributor D The individual tubes o1 each of the distributors D will h rc their circuits completed through individual glow tubes in the area U U corresponding to areas U U ot the area scanned. In this manner the effect of the oscillator current controlled by the light responsive devices in the total area scanned will be reproduced by the glow tubes at the receiving station and the image will be thereupon reproduced.

Olwiously it will be necessary tor the individual tubes of each of the distributors D D to operate in synchronism with tubes of the corresponding distributors he operation of the tubes of rinitors D D is controlled by p ises 0'5 current applied to leads 73 from the source 72 and interrupter 71. Interrupter 71 may be connected by shafts and ears to interrupter 5. he gear ratio will N to 1. N will represent the number of elements in each of the individual areas to be scanned, such as area U or in other words the total. number of tubes such as A N in each of the distributors. Gun rent from source 72 and interrupter 'll is transmitted through filters F and over the line and applied to the grid circuits of the individual tubes of each of the distributors D D in a manner similar to that shown in Fig. 3. With such an arrangement the tubes of corresponding distributors will operate in synchronism with each other. As heretofore pointed out current from source 7 and interrupter 5 transmitted through filters F keeps tubes S S and tubes S in synchronism. Other means for keeping the tubes operating in synchronism may be used if desired,

This invention also provides-a means for operating printing telegraph apparatus without requiring a mechanically distributor of the type heretofore employed. Referring to Fig. 1, key 6 may be used as the starting key, while contacts T T T represent the contacts in a tape transmitter, of the type well known in the art, which is ordinarily used to transmit printing telegraph signals from perforated tape, In the ordinary case of 5-unit Baudot code N would therefore be five. At the receiving station,

as shown in Fi 2 the lam )8 G to G would be replaced by the electromagnets of the receiving teletypewriter, rectifiers of a suitable type being provided to convert the alternating current to direct current adapted to oper- 'ate the electromagnets. It is at once apparent that the arrangements shown in Figs. 1 and 2 are readily applicable to the printing telegraph art and enable a group oi": gas-filled discharge tubes to replace the mechanically operated rotating distributors heretofore employed.

lVhile the invention has been disclosed as embodied in certain specific arrangements which are deemed desirable, it is understood that it is capable of embodiment in many and other widely varied forms without departing from the spirit of the invention as defined by the appended claims,

lVhat is claimed is: V

1. A signaling system comprising a line extending from a transmittingstation to areceiving station, an oscillator associated with said line at said transmitting station, means for applying a synchronizing current to said line at said transmitting station, a series of gas-filled discharge tubes at said transmitting station adapted to be operated in sequence by said synchronizing current, means for causing each of said tubes to release before the succeeding tube ot the series is operated, means controlled by each of said tubes for closing individual operating circuits for said oscillator, means for varying the resistance of each of said. individual operating circuits of said oscillator, a series of gas-filled discharge tubes at said receiving station corresponding to said series of tubes at said transmitting station and sequentially operated by said synchronizing current in synchronism with the tubes at said transmitting station, signaling means individual to each of said tubes at said receiving station, and means controlled by each of the tubes at said receiving station for operatively con necting its individual signaling means to said line.

2. A signaling system comprising a line, transmit-ting apparatus associated with said line, said transmitting apparatus comprising, an oscillator associated with said line, means moving rotary,

for applying pulses of synchronizing current to said line, a series of gas-filled discharge tubes, means for applying said pulsating synchronizing current to said tubes, the first tube of said series being adjusted so that it will normally be operated by the Voltage of the first pulse of said synchronizing current and the other tubes being adjusted so that they normally will not be operated by the voltage of said synchronizing current, auxiliary gas-filled discharge tubes individual to the tubes of said series and adapted to be operated thereby, means controlled by each of said auxiliary tubes when operated for releasing its operating tube before the next succeeding pulse of synchronizing current has been transmitted, and for adjusting the next succeeding tube in the series so that it will be operated on the voltage of the next succeeding pulse of said synchronizing current, means controlled by each of the tubes of said series for closing individual operating circuits for said oscillator, means for varying the resistance of each of said individual operating circuits of said oscillator, and receiving apparatus associated with said line, said receiving apparatus comprising a series of gas-filled discharge tubes corresponding to the tubes of said transmitting apparatus and operated by said synchronizing current in svnchronism with the tubes of said transmitting apparatus, and receiving circuits controlled by said series of tubes in said receiving apparatus.

A signaling system comprising a line extending from a transmitting station to a receiving station, a series of gas-filled discharge tubes at said transmitting station, signaling circuits individual to each of the tubes of said series and each adapted to be operatively associated with said line by the operation of each of the tubes of said series, signal transmitting devices in each of said individual signaling circuits, means for operating and. releasing the tubes of said series sequentially, a series of gas-filled discharge tubes at said receiving station corresponding to the tubes of said series at said transmitting station, means for operating. the tubes of said series at said receiving station in synchronism with the tubes of said series at said sending station, and signal responsive means individual to and controlled by each of the tubes of said series at said receiving station.

4. A signaling system comprising a line extending from a transmitting station to a receiving station, an oscillator associated with said line at said transmitting station, means for applying a synchronizing current to said line at said transmitting station, a series of gas-filled discharge tubes at said transmitting station adapted to be operated in sequence by said synchronizing current, means for causing each of said tubes to release before the succeeding tube of the series is operated, means controlled by each of said tubes for closing individual operating circuits for said oscillator, individual ligat responsive devices for varying the resistance of each of said individual operating circuits of said oscillator, a series of gas-filled discharge tubes at said receiving station corresponding to said series of tubes at said transmitting station and sequentially operated by said synchronizing current in synchronism with the tubes at said transmitting station, visual signaling means individual to each of said tubes at said receiving station, and means controlled by each of the tubes at said receiving station for operatively connecting its individual visual signaling means to said line.

5. A signaling system comprising a line, transmitting apparatus associated with said line, said transmitting apparatus comprising an oscillator associated with said line, a series of gas-filled discharge tubes, means for operating and releasing the tubes of said series in sequence, means for extending the operating circuit of said oscillator over the cathodeanode circuits of each of the tubes of said series when operated, a distributor associated with each of the tubes of said series, each of said distributors comprising a series of gasfilled discharge tubes adapted to be operated and released in sequence, means for extending the operating circuit of said oscillator from the cathode-anode circuits of each of the tubes of said first series over the cathode-anode circuits of the series of tubes when operated in the distributor associated therewith, signaling circuits individual to each of the tubes of each of said distributors for completing the cathode-anode circuits of each of said tubes, receiving apparatus associated with said line, said receiving apparatus comprising a plurality of gas-filled tubes associated with said line and corresponding in number and arrangement and operating in synchronism with the gas-filled tubes of said transmitting apparatus, and signal responsive circuits controlled by the tubes at said receiving station.

6. A signaling system comprising a line,

- transmitting apparatus associated with said line, said transmitting apparatus comprising an oscillator associated with said line, amaster series of gas-filled discharge tubes, means for applying to said line and to said master series of tubes a synchronizing current of a first frequency for operating and releasing the tubes of said series in sequence, means for extending the operating circuit of said oscillator over the cathodeanode circiuts of each of the tubes of said master series when operated, a distributor associated with each of the tubes of said master series, each of said distributors comprising a series of gas-filled discharge tubes, means for applying to said line and to each of said distributors a synchronizing current of a second frequency whereby the tubes of each series in each distributor may be operated in sequence and so that each series of tubes will complete one cycle of operations while individual ones of the tubes of said master series are operated, means for extending the operating circuit of said oscillator from the cathode-anode circuits of each of the tubes of said master series over the cathode-anode circuits of the series of tubes when operated in the distributor associated therewith, signaling circuits indi vidual to each of the tubes of each of said distributors for completing the cathodeanode circuits of each of said tubes, a receiving circuit associated with said line, a second master series of gas-filled discharge tubes corresponding to the tubes of said first master series, means for applying to the tubes of said second master series the synchronizing current of said first frequency to cause said tubes to operate and release in synchronism with the tubes of said first master series, means for extending said receiving circuit over the cathode-anode circuits of each of the tubes of said second master series when operated, a distributor associated with each of the tubes of said second master series, each of said distributors comprising a series of gasfilled discharge tubes similar to the series of tubes in the corresponding distributors of said transmitting apparatus, means for applying to each of said last mentioned distributors said synchronizing current of said second frequency whereby the tubes of said distributors will operate in synchronism with the tubes of said distrbutors of said transmitting apparatus, means for extending said receiving circuit from the cathode-anode cir cuits of each of the tubes of said second mas ter series over the cathode-anode circuits or" the series of tubes when operated in the distributor associated therewith, and signaling circuits individual to and controlled by each of the tubes of each of said distributors of said receiving apparatus.

In testimony whereof, I have signed my name to this specification this 29th day of September 1932.

CHARLES S. DEMAREST. 

